Hi, I’ve never done a human before so I am going to try to get one as photo real as I can.
don’t neglect the ears. I would duplicate the current head, or ear, sculpt the ear using dynatopo, then use retopo / snapping on the original ear area, using the sculpted ear as a guide.
You can use some better topology around the mouth area. That will really help you get that area looking good. your head seems a bit wide. Also, is there a particular model you are using for reference? For a first attempt, this is really good. My first heads looked really bad.
For a first attempt it looks great, but maybe it’s best if you sculpt a great head first and then retopologize. That way you get a more realistic (after some practice 
) form. But looking good already keep up the good work!